Reflective marker with alignment feature

ABSTRACT

Described is a device comprising a retro-reflective marker sphere comprising: a core ball comprising: a generally spherical body portion, a mounting base extending from one end of the body portion of the core ball, and a mounting recess having a recess opening in the mounting base and extending into the body portion of the core ball, and a retro-reflective covering on the core ball, the retro-reflective covering comprising an opening through which the mounting base of the core ball extends, wherein a flat lower surface of the mounting base is spaced proximally from a lower edge of the opening of the retro-reflective covering, and wherein the mounting recess includes an interior screw thread for engaging an exterior screw thread of a mounting post when the retro-reflective marker sphere is mounted on the mounting post.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority to U.S. Provisional PatentApplication No. 61/565,099 to Shafer, entitled NOVEL SNAP-ON-SPHERE,filed Nov. 30, 2011, which is incorporated herein by reference in itsentirety. This application also claims priority to the followingapplications filed Feb. 29, 2011 to the same inventors as the presentapplication: application Ser. No. 13/408,046 entitled “RADIOPAQUE CORE,”application Ser. No. 13/408,126 entitled “RETRO-REFLECTIVE MARKER WITHSNAP ON THREADED POST,” application Ser. No. 13/408,272 entitled“MATERIAL THICKNESS CONTROL OVER RETRO-REFLECTIVE MARKER,” applicationSer. No. 13/408,386 entitled “REFLECTIVE MARKER BEING RADIO-OPAQUE FORMRI,” application Ser. No. 13/408,387 entitled “PACKAGING FORRETRO-REFLECTIVE MARKERS,” application Ser. No. 13/408,317 entitled“HIGH REFLECTIVITY RETRO-REFLECTIVE MARKER,” application Ser. No.13/408,124 entitled “RETRO-REFLECTIVE MARKER INCLUDING COLORED MOUNTINGPORTION,” and application Ser. No. 13/408,070 entitled “MARKER SPHEREINCLUDING EDGED OPENING TO AID IN MOLDING,” the entire content anddisclosures of which are incorporated herein by reference in theirentirety.

BACKGROUND

1. Field of the Invention

The present invention relates to retro-reflective markers forimage-guided surgery.

2. Related Art

Systems for obtaining coordinates of a point or points of interestinclude marker-tracking systems. Such marker-tracking systems typicallyrely on objects having one or more markers affixed thereto. The markersthat are affixed to the object may be active markers (e.g.,light-emitting diode markers), passive markers (e.g., retro-reflectivemarkers) or a combination of active and passive markers. In a medicalapplication context, such as image-guided surgery, a user (e.g., adoctor) touches the surface of interest (e.g., a surface of a patient'sbody) using the distal tip of an object (e.g., a probe or a surgicalinstrument). A marker-sensing device (e.g., a pair of cameras) views themarker(s) affixed to the object. On the basis of the known locations ofthe cameras and the location(s) of the marker(s) as seen by each camera,such systems calculate the three-dimensional coordinates of themarker(s). Then, on the basis of the known relationship between thelocation(s) of the marker(s) and the location of the object tip, themarker-tracking system determines the coordinates of the object's tip.With the object's tip on the surface, those coordinates also correspondto the coordinates of the surface at that point.

SUMMARY

According to a first broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, and a mountingrecess extending into the body portion of the core ball, and aretro-reflective covering on the core ball, wherein the retro-reflectivecovering has an opening aligned with the mounting recess of the coreball, wherein the mounting recess includes one or more interiorengagement structures for engaging one or more exterior engagementstructures of a mounting post when the retro-reflective marker sphere ismounted on the mounting post, and wherein the core ball is greater than12% radiopaque.

According to a second broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, and a mountingrecess extending into the body portion of the core ball, and aretro-reflective covering on the core ball, wherein the retro-reflectivecovering has an opening aligned with the mounting recess of the coreball, and wherein the mounting recess includes a semi-locking interiorscrew thread for engaging an exterior screw thread of a mounting postand for causing an audible snap when the retro-reflective marker sphereis snapped onto the mounting post.

According to a third broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, and a mountingrecess extending into the body portion of the core ball, and aretro-reflective covering on the core ball, wherein the retro-reflectivecovering has an opening aligned with the mounting recess of the coreball, wherein the mounting recess includes one or more interiorengagement structures for engaging one or more exterior engagementstructures of a mounting post when the retro-reflective marker sphere ismounted on a mounting post, and wherein the thickness of theretro-reflective covering varies by no more than 0.00762 cm.

According to a fourth broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, and a mountingrecess extending into the body portion of the core ball, and aretro-reflective covering on the core ball, wherein the retro-reflectivecovering has an opening aligned with the mounting recess of the coreball, wherein the mounting recess includes one or more interiorengagement structures for engaging one or more exterior engagementstructures of a mounting post when the retro-reflective marker sphere ismounted on a mounting post, and wherein the core ball comprises an MRIfilling material contained in the core ball.

According to a fifth broad aspect, the present invention provides apackage comprising: a pocket layer including one or more pockets forreceiving one or more retro-reflective marker spheres, and one or morebacking layers joined to the pocket layer, wherein at least one of theone or more backing layers includes a recess for receiving a polygonalmounting base of a retro-reflective marker sphere of the one or moreretro-reflective marker spheres to thereby maintain the retro-reflectivemarker sphere in a right-side-up orientation.

According to a sixth broad aspect, the present invention provides apackage comprising: a pocket layer including one or more pockets forreceiving one or more respective retro-reflective marker spheres, andone or more backing layers joined to the pocket layer, wherein at leastone of the one or more backing layers includes a mounting base openingfor receiving a mounting base of a retro-reflective marker sphere of theone or more retro-reflective marker sphere so that the mounting baseextends through the mounting base opening to thereby maintain theretro-reflective marker sphere in a right-side-up orientation.

According to a seventh broad aspect, the present invention provides apackage comprising: a pocket layer including one or more pockets forreceiving one or more retro-reflective marker spheres, one or morebacking layers joined to the pocket layer by an adhesive, and aretro-reflective marker sphere contained in the package, wherein theadhesive has a peel strength of no greater than 22.24 N of force.

According to an eighth broad aspect, the present invention provides apackage comprising: a pocket layer including one or more pockets forreceiving one or more retro-reflective marker spheres, one or morebacking layers joined to the pocket layer, wherein at least one of theone or more backing layers comprises a rupturable material joined to thepocket layer, and a retro-reflective marker sphere contained in thepackage.

According to a ninth broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, and a mountingrecess extending into the body portion of the core ball, and aretro-reflective covering on the core ball, wherein the retro-reflectivecovering has an opening aligned with the mounting recess of the coreball, wherein the mounting recess includes one or more interiorengagement structures for engaging one or more exterior engagementstructures of a mounting post when the retro-reflective marker sphere ismounted on a mounting post, and wherein the retro-reflective covering isgold-colored.

According to a tenth broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, and a mountingrecess extending into the body portion of the core ball, and aretro-reflective covering on the core ball, wherein the retro-reflectivecovering has an opening aligned with the mounting recess of the coreball, wherein the mounting recess includes one or more interiorengagement structures for engaging one or more exterior engagementstructures of a mounting post when the retro-reflective marker sphere ismounted on a mounting post, and wherein the retro-reflective covering ischrome-colored.

According to an eleventh broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, and a mountingrecess extending into the body portion of the core ball, and aretro-reflective covering on the core ball, wherein the retro-reflectivecovering has an opening aligned with the mounting recess of the coreball, wherein the mounting recess includes one or more interiorengagement structures for engaging one or more exterior engagementstructures of a mounting post when the retro-reflective marker sphere ismounted on a mounting post, and wherein the retro-reflective covering iswhite-colored.

According to a twelfth broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, a mounting baseextending from one end of the body portion of the core ball, and amounting recess having a recess opening in the mounting base andextending into the body portion of the core ball, and a retro-reflectivecovering on the core ball, the retro-reflective covering comprising anopening through which the mounting base of the core ball extends,wherein the mounting recess includes one or more interior engagementstructures for engaging one or more exterior engagement structures of amounting post when the retro-reflective marker sphere is mounted on themounting post, wherein a flat lower surface of the mounting base isspaced proximally from a lower edge of the opening of theretro-reflective covering, and wherein the mounting base has analignment indicator on one or more sides of the mounting base.

According to a thirteenth broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, a mounting baseextending from one end of the body portion of the core ball, and amounting recess having a recess opening in the mounting base andextending into the body portion of the core ball, and a retro-reflectivecovering on the core ball, the retro-reflective covering comprising anopening through which the mounting base of the core ball extends,wherein the mounting recess includes one or more interior engagementstructures for engaging one or more exterior engagement structures of amounting post when the retro-reflective marker sphere is mounted on themounting post, wherein a flat lower surface of the mounting base isspaced proximally from a lower edge of the opening of theretro-reflective covering, and wherein the mounting base has a polygonalcross-section in a plane perpendicular to an axis of the core ball.

According to a fourteenth broad aspect, the present invention provides adevice comprising a retro-reflective marker sphere comprising: a coreball comprising: a generally spherical body portion, a mounting baseextending from one end of the body portion of the core ball, and amounting recess having a recess opening in the mounting base andextending into the body portion of the core ball, and a retro-reflectivecovering on the core ball, the retro-reflective covering comprising anopening through which the mounting base of the core ball extends,wherein the core ball is a single-piece core ball, wherein a flat lowersurface of the mounting base is spaced proximally from a lower edge ofthe opening of the retro-reflective covering, and wherein the mountingrecess includes an interior screw thread for engaging an exterior screwthread of a mounting post when the retro-reflective marker sphere ismounted on the mounting post.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate exemplary embodiments of thepresent invention and, together with the general description given aboveand the detailed description given below, serve to explain the featuresof the present invention.

FIG. 1 is a perspective view of a retro-reflective marker sphereaccording to one embodiment of the present invention.

FIG. 2 is an exploded view of the retro-reflective marker sphere of FIG.1, with divets in a core ball and interior structures in a mountingrecess of the core ball of the retro-reflective marker sphere omittedfor simplicity of illustration.

FIG. 3 is a bottom plan view of the retro-reflective marker sphere ofFIG. 1.

FIG. 4 is a cross-sectional view of the retro-reflective marker sphereof FIG. 1 taken along line A-A of FIG. 3.

FIG. 5 is a side view of the core ball of the retro-reflective markersphere of FIG. 1.

FIG. 6 is a bottom plan view of the core ball of FIG. 5.

FIG. 7 is a perspective view of a medical device, mounted on a humanfoot, on which are mounted retro-reflective marker spheres according toone embodiment of the present invention.

FIG. 8 is a perspective view of a threaded mounting post on an arm ofthe medical device of FIG. 7.

FIG. 9 is a cross-sectional view of the retro-reflective marker sphereof FIG. 1 mounted on the threaded mounting post of FIG. 8.

FIG. 10 is a cross-sectional view of a snap-on retro-reflective markersphere according to one embodiment of the present invention.

FIG. 11 is a cross-sectional view of the snap-on retro-reflective markersphere mounted on the threaded mounting post of FIG. 8.

FIG. 12 is a close-up view of the dashed-circled region of FIG. 11.

FIG. 13 is a bottom perspective view of a retro-reflective marker sphereaccording to one embodiment of the present invention.

FIG. 14 is a bottom perspective view of a retro-reflective marker sphereaccording to one embodiment of the present invention.

FIG. 15 is a bottom perspective view of a retro-reflective marker sphereaccording to one embodiment of the present invention.

FIG. 16 shows a retro-reflective marker sphere mounting base having acontrasting color with respect to a retro-reflective covering of theretro-reflective marker sphere according to one embodiment of thepresent invention.

FIG. 17 shows a retro-reflective marker sphere mounting base with oneside having a contrasting color with respect to a retro-reflectivecovering of the retro-reflective marker sphere according to oneembodiment of the present invention.

FIG. 18 shows a retro-reflective marker sphere mounting base having analignment line on one side according to one embodiment of the presentinvention.

FIG. 19 shows a retro-reflective marker sphere mounting base having analignment dot on one side according to one embodiment of the presentinvention.

FIG. 20 shows a retro-reflective marker sphere mounting base havingalignment stars on at least two sides according to one embodiment of thepresent invention.

FIG. 21 shows a blister strip of packaged retro-reflective markerspheres according to one embodiment of the present invention.

FIG. 22 is a cross-sectional view of a packaged retro-reflective markersphere according to one embodiment of the present invention.

FIG. 23 is a cross-sectional view of a packaged retro-reflective markersphere according to one embodiment of the present invention.

FIG. 24 is a bottom plan view of the packaged retro-reflective markersphere of FIG. 23.

FIG. 25 is a cross-sectional view of a packaged retro-reflective markersphere according to one embodiment of the present invention.

FIG. 26 is a bottom plan view of the packaged retro-reflective markersphere of FIG. 25.

FIG. 27 shows a blister card of packaged retro-reflective marker spheresaccording to one embodiment of the present invention.

FIG. 28 is a perspective view of a retro-reflective marker sphere thatmay be used in various embodiments of the present invention.

FIG. 29 is an exploded view of the retro-reflective marker sphere ofFIG. 28, with divets in a core ball and interior structures in amounting recess of the core ball of the retro-reflective marker sphereomitted for simplicity of illustration.

FIG. 30 is a bottom plan view of the retro-reflective marker sphere ofFIG. 28.

FIG. 31 is a side view of the retro-reflective marker sphere of FIG. 28.

FIG. 32 is a perspective view of the core ball of the retro-reflectivemarker sphere of FIG. 28.

FIG. 33 is a side view of the core ball of FIG. 32.

FIG. 34 is a cross-sectional view of the core ball of FIG. 32 takenalong line B-B of FIG. 33.

FIG. 35 is a close-up view of one of the two dashed-circled regions ofFIG. 34.

FIG. 36 is a close-up view of the other dashed-circled region of FIG.34.

FIG. 37 is a perspective view of a medical device, mounted on a humanfoot, on which are mounted retro-reflective marker spheres according toone embodiment of the present invention.

FIG. 38 is a perspective view of a snap-on mounting post on an arm ofthe medical device of FIG. 37.

FIG. 39 is a cross-sectional view of the retro-reflective marker sphereof FIG. 1 mounted on the snap-on mounting post of FIG. 38.

FIG. 40 is a cross-sectional view of a packaged retro-reflective markersphere according to one embodiment of the present invention.

FIG. 41 is a cross-sectional view of a packaged retro-reflective markersphere according to one embodiment of the present invention.

FIG. 42 is a bottom plan view of the packaged retro-reflective markersphere of FIG. 41.

FIG. 43 is a cross-sectional view of the core ball of FIG. 32 takenalong line B-B of FIG. 33 according to an alternate embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Definitions

Where the definition of terms departs from the commonly used meaning ofthe term, applicant intends to utilize the definitions provided below,unless specifically indicated.

For purposes of the present invention, it should be noted that thesingular forms, “a,” “an” and “the,” include reference to the pluralunless the context as herein presented clearly indicates otherwise.

For purposes of the present invention, directional terms such as “top,”“bottom,” “upper,” “lower,” “above,” “below,” “left,” “right,”“horizontal,” “vertical,” “up,” “down,” etc., are used merely forconvenience in describing the various embodiments of the presentinvention. The embodiments of the present invention may be oriented invarious ways. For example, the diagrams, apparatuses, etc., shown in thedrawing figures may be flipped over, rotated by 90° in any direction,reversed, etc.

For purposes of the present invention, the term “alignment indicator”refers to a symbol or other type of indicator on one or more sides of amounting base of a retro-reflective marker sphere that may be used todetermine if the retro-reflective marker sphere is aligned properly onits mounting post. Examples of alignment indicators include: lines,dots, letters, numbers, stars, shapes, etc.

For purposes of the present invention, the term “audible” refers to asound that may be heard by an human being having normal hearing.

For purposes of the present invention, the term “backing layer” refer tothe one or more layers of a blister pack joined to the pocket layer tothereby contain an item in the blister pack. If the backing layer has anopening, part of the item contained in the blister pack may protrudethrough the opening. Suitable materials for use as a backing layerinclude paper, cardboard, plastic, metal foil, such as aluminum foil,mylar, Tyvek® (flashspun high-density polyethylene fiber materialmanufactured by Dupont), etc. In some blister packs of the presentinvention, there may be two or more backing layers. For example, onebacking layer may be made of cardboard, a stiff plastic, etc., toprovide structural stability to the blister pack, and a second backinglayer may be made of a metal foil that is rupturable.

For purposes of the present invention, the term “blister card” refers toa blister package comprising a connected two-dimensional set of blisterpacks.

For purposes of the present invention, the term “blister pack” refers tothe common meaning of the term “blister pack,” i.e., a packagecomprising a pocket formed of a formable material such as a plastic andone or more backing layers that seal the package. Examples of formablematerials include thermoformable or thermosettable plastics.

For purposes of the present invention, the term “blister package” refersto a package comprising one or more blister packs.

For purposes of the present invention, the term “blister strip” refersto a blister package comprising a one-dimensional strip of blisterpacks.

For purposes of the present invention, the term “chrome-colored” refersto a bright silver mirrored reflective finish. Examples ofchrome-colored retro-reflective coverings include tapes, inks, emergencyreflective sign paints, emergency reflective road markings, etc.

For purposes of the present invention, the term “centipoise” refers to aunit of dynamic viscosity and is the amount of force necessary to move alayer of liquid in relation to another liquid. Centipoise is consideredthe standard unit of measurement for fluids of all types. It is onehundredth of a poise. Water at approximately 70° F. (21° C.) is aboutone centipoise. When determining centipoise, all other fluids arecalibrated to the viscosity of water. Blood has a viscosity of 10centipoise, and ethylene glycol has a viscosity of 15 centipoise.

For purpose of the present invention, the term “engage” refers to acontacting and/or interlocking interaction between two or moreengagement structures.

For purposes of the present invention, the term “engagement structure”refers to a structure on a first object, such as a retro-reflectivemarker sphere or a post, that is shaped to engage one or more engagementstructures on a second object, such as a post or a retro-reflectivemarker sphere. Examples of engagement structures include interior screwthreads, exterior screw threads, ledges, tabs, recesses, rims, etc.

For purposes of the present invention, the term “exterior snap-onengagement structure” refers to an engagement structure on an exteriorsurface of an object, such as a mounting post. Examples of exteriorsnap-on engagement structures include the exterior screw thread in FIG.12; the recess in the mounting post shown in FIGS. 38 and 39; etc.

For purposes of the present invention, the term “generallyhemispherical” refers to an object, such as a retro-reflective markersphere upper or lower retro-reflective covering, that is at least 50%hemispherical in shape over its surface. An object that is generallyhemispherical in shape may include one or more openings and/or recesses.An object that is generally hemispherical in shape, such as aretro-reflective marker sphere upper or lower retro-reflective covering,may be comprised of one piece or two or more pieces. An object that isgenerally hemispherical in shape may be hollow or solid.

For purposes of the present invention, the term “generally spherical”refers to an object, such as a retro-reflective marker sphere coveringor a core ball, that is at least 50% spherical in shape over itssurface. An object that is generally spherical in shape may include oneor more openings and/or recesses. An object that is generally sphericalin shape, such as a retro-reflective marker sphere covering, may becomprised of one piece or two or more pieces. An object that isgenerally spherical in shape may be hollow or solid.

For purposes of the present invention, the term “gold-colored” refers toa bright gold reflective finish. Examples of gold-coloredretro-reflective coverings include tapes, inks, paints for cars, bikesand motorcycles, decorative markings for cars, bikes and motorcycles,etc.

For purposes of the present invention, the term “interior snap-onengagement structure” refers to an engagement structure on an interiorsurface or recess of an object, such as a retro-reflective markersphere. Examples of interior snap-on engagement structures include thesemi-locking interior screw thread shown in FIGS. 10, 11 and 12; theraised rim shown in FIGS. 34 and 39; etc.

For purposes of the present invention, the term “manually removable”refers to a pocket layer joined to a backing layer by an adhesive thathas a peel strength of no greater than 5 lbs. (22.24 N) of force. In oneembodiment of the present invention, a manually removable adhesive mayhave a peel strength of no greater than 3 lbs. (13.34 N) of force.

For purposes of the present invention, the terms “magnetic resonanceimaging” (MRI), “nuclear magnetic resonance imaging” (NMRI), or“magnetic resonance tomography” (MRT) refer to a medical imagingtechnique used in radiology to visualize detailed internal structures.MRI makes use of the property of nuclear magnetic resonance (NMR) toimage nuclei of atoms inside the body. An MRI machine uses a powerfulmagnetic field to align the magnetization of some atomic nuclei in thebody, and radio frequency fields to systematically alter the alignmentof this magnetization. This causes the nuclei to produce a rotatingmagnetic field detectable by the scanner. This information is recordedto construct an image of the scanned area of the body. Magnetic fieldgradients cause nuclei at different locations to rotate at differentspeeds. By using gradients in different directions 2D images or 3Dvolumes can be obtained in any arbitrary orientation. MRI provides goodcontrast between the different soft tissues of the body, which makes itespecially useful in imaging the brain, muscles, the heart, and cancerscompared with other medical imaging techniques such as computedtomography (CT) or X-rays. Unlike CT scans or traditional X-rays, MRIdoes not use ionizing radiation.

For purposes of the present invention, the term “non-rupturablematerial” refers to a material used as a backing layer for a blisterpack that is not designed to be manually ruptured by a user.

For purposes of the present invention, the term “pocket layer” refers tothe layer of a blister pack including a pocket or bubble. Examples ofmaterials that may be used in pocket layers includes transparent ortranslucent plastics such as clear or colored polyvinyl chloride (PVC),rigid PVC, duplex structures such as PVC/PCTFE (polyvinylchloride/polychlorotrifluoroethylene), triplex laminates such asPVC/PE/PCTFE (polyvinylchloride/polyethylene/polychlorotrifluoroethylene), etc.

For purposes of the present invention, the term “polygon” without anymodifier refers to both regular and irregular polygons. Similarly, anobject that is “polygonal” in shape may be in the shape of a regular oran irregular polygon. For purposes of the present invention, a polygonor an object that is polygonal in shape may have rounded corners.

For purposes of the present invention, the term “proximal” refers to thedirection toward the end of a retro-reflective marker sphere where amounting base of the retro-reflective marker sphere is located, towardthe base of a mounting post or toward the end of a medical device thatis held by a user or that is used to mount the medical device in place.For purposes of the present invention, the term “distal” refers to thedirection opposite the “proximal” direction.

For purposes of the present invention, the term “radiopaque” refers toan object, such as a retro-reflective marker sphere or a core ball, thatblocks x-rays or other types of electromagnetic radiation such as UV(ultraviolet) light. A non-radiopaque material, such as a plastic, maybe made radiopaque by adding a radiopaque dopant, such as barium, to thematerial. Examples of radiopaque materials that may be used as dopantsto make radiopaque core balls and radiopaque retro-reflective markerspheres of the present invention include calcium phosphate cement,radiopaque polymer salts, iodine agents such as barium sulfate, metalagents such as tantalum, etc.

For purposes of the present invention, the term “retro-reflective”refers to the conventional meaning of the term “retro-reflective,” i.e.,an object or surface that reflects light back to its source with aminimum scattering of light. Retro-reflective materials such asretro-reflective tape and paint may be made in a variety of colors. Forexample, retro-reflective tapes and materials are commonly used inpavement marking tapes, transport trailer tapes, and safety markers orcones in colors such as white, yellow, red and orange.

For purposes of the present invention, the term “retro-reflective markersphere” refers to a retro-reflective marker sphere that isretro-reflective and/or has a retro-reflective covering on at least partof the retro-reflective marker sphere. In some embodiments of thepresent invention, the retro-reflective covering covers at least 95% ofthe retro-reflective marker sphere.

For purposes of the present invention, the term “right-side-uporientation” refers to a retro-reflective marker sphere oriented in ablister pack so that the proximal end of the retro-reflective markersphere is adjacent to the backing layer of the blister pack.

For purposes of the present invention, the term “rupturable material”refers to a material used as a backing layer for a blister pack that maybe ruptured by a user pushing out a retro-reflective marker sphereenclosed in the blister pack through the backing layer, thereby allowingthe retro-reflective marker sphere to be removed from the blister pack.Examples of rupturable materials include paper, cardboard, metal foilssuch as aluminum, some types of plastics, etc.

For purposes of the present invention, the term “semi-locking screwthread” refers to a first screw thread which includes a thread that hasa ridge that does not fully mate with the groove of a second screwthread that engages the first screw thread.

For purposes of the present invention, the term “single-piece” refers toan object that is made of a single piece, as opposed to being made oftwo or more pieces.

For purposes of the present invention, the term “snap-on mounting post”refers to a mounting post that is designed to allow a snap-onretro-reflective marker sphere to be snapped onto the mounting post.

For purposes of the present invention, the term “snap-onretro-reflective marker sphere” refers to a retro-reflective markersphere that snaps onto a mounting post of a medical device. The mountingpost may be either a snap-on mounting post or a threaded mounting post.For example, in one embodiment, the present invention provides aretro-reflective marker sphere that is designed to be snapped onto athreaded mounting post.

For purposes of the present invention, the term “threaded mounting post”refers to a mounting post that includes one or more exterior screwthreads that is designed to allow a retro-reflective marker sphere witha threaded mounting recess to be screwed onto the mounting post.

For purposes of the present invention, the term “threadedretro-reflective marker sphere” refers to a retro-reflective markersphere that includes one or more interior screw threads in a mountingrecess of the retro-reflective marker sphere.

For purposes of the present invention, the term “two-pieceretro-reflective covering” refers to a retro-reflective covering thatcomprises only two pieces. Examples of two-piece retro-reflectivecoverings are shown in FIGS. 1, 2, 3, 4, 5, 6, 10, 28, 29, 30, 31, 32,33, 34, 35 and 36.

For purposes of the present invention, the term “viscosity” refers tothe measure of a fluid's resistance to flow and may be thought of asfluid friction. Thinner liquids, such as water, have lower viscosities,while thicker liquids like oil have higher viscosities.

For purposes of the present invention, the term “white-colored” refersto a white finish that reflects light back towards the source of thelight. Examples of white-colored retro-reflective coverings includepavement marking tapes, transport trailer tapes, and safety markers orcones.

DESCRIPTION

Retro-reflective marker spheres, also referred to as passive reflectivemarkers, are widely used in image guidance systems. For example,retro-reflective marker spheres have been used in military,entertainment, sports, and medical applications, and for validation ofcomputer vision and robotics. In filmmaking, retro-reflective markerspheres have been used in recording actions of human actors and usingthat information to animate digital character models in 2D or 3Dcomputer animation. In motion-capture sessions, movements of one or moreactors are sampled many times per second, although with most techniques(recent developments from Weta Digital use images for 2D motion captureand project into 3D), motion capture records only the movements of theactor, not his or her visual appearance. This animation data is mappedto a 3D model so that the model performs the same actions as the actor.This is comparable to the older technique of rotoscope, such as thatused in Ralph Bakshi's The Lord of the Rings (1978) and American Pop(1981) animated films in which the motion of an actor was filmed, andthen the film was used as a guide for the frame-by-frame motion of ahand-drawn animated character. Camera movements may also be motioncaptured so that a virtual camera in the scene will pan, tilt, or dollyaround the stage driven by a camera operator while the actor isperforming, and the motion capture system can capture the camera andprops as well as the actor's performance. This allows thecomputer-generated characters, images and sets to have the sameperspective as the video images from the camera. A computer processesthe data and displays the movements of the actor, providing the desiredcamera positions in terms of objects in the set. Retroactively obtainingcamera movement data from the captured footage is known as match movingor camera tracking.

In medicine, one-time-use retro-reflective markers spheres are used toaid registration and instrument tracking during image guided surgeryprocedures such as neurological procedures, spin procedure andorthopedic procedures.

Typically, retro-reflective marker spheres have a high coefficient ofretro-reflection on the external surface to provide feedback to thesystem/camera. These surfaces consist of micro glass spheres thatreflect light. However, because medical retro-reflective marker spheresare often used within the sterile field, the spheres may need to besterilized using processes such as ethylene oxide (ETO) gassterilization, gamma-ray sterilization and electron beam (E-beam)sterilization. These sterilization processes may negatively impactpolymers and may degrade the polymer structure. For this reason, formedical applications, retro-reflective marker spheres may need to bemade of materials that are able to withstand the impact ofsterilization.

Depending on the medical application, different numbers and arrangementsof retro-reflective marker spheres may be mounted on various types ofsurgical tooling that may be used. For example, from two to fiveretro-reflective marker spheres may mounted on a surgical probe.Depending on the type of posts used on a particular surgical probe, eachof the retro-reflective marker spheres is mounted on a surgical probeseither by screwing the retro-reflective marker sphere onto a threadedmounting post of the surgical probe or by snapping the retro-reflectivemarker sphere onto a snap-on post of the surgical probe. Once mounted ona surgical problem, retro-reflective marker spheres provide an accuracyreference point for the surgical probe in three-dimensional space.

In one embodiment, the present invention provides a threaded sterileretro-reflective marker sphere that includes a mounting base forimproved mounting on a threaded mounting post of a medical device usedin image-guided surgical procedures. The retro-reflective marker spherecomprises an interior ball on which are mounted two retro-reflectivehemispheres to form a spherical covering. A retro-reflective markersphere includes a threaded mounting recess in the interior ball at oneend into which a threaded mounting post of the medical device extendswhen the retro-reflective marker sphere is mounted on the medicaldevice. The lower sphere includes an opening aligned with a mountingrecess in the interior core ball. Conventionally, the interior screwthread in the mounting recess of a retro-reflective marker sphere isused to determine the point at which the retro-reflective marker sphereis fully mounted on a threaded mounting post. The retro-reflectivemarker sphere is considered fully mounted when the retro-reflectivemarker sphere can be turned no more on a threaded mounting post of amedical device. The mounting recess of a conventional retro-reflectivemarker sphere includes a thread along the entire length of the mountingrecess. In contrast, in one embodiment of the present invention, theinterior core ball includes a mounting base that extends beyond the edgeof the bottom hemisphere so that the mounting base is the only part ofthe retro-reflective maker sphere that contacts the base of the threadedmounting post. In one embodiment of the present invention, aretro-reflective marker sphere includes a mounting recess having aninterior screw thread to allow the retro-reflective marker sphere to bemounted on threaded mounting post, but the interior screw thread doesnot extend all the way to the top of the mounting recess. A non-threadedportion of the mounting recess is used for alignment of theretro-reflective marker sphere in the axial direction of the threadedmounting post.

FIGS. 1, 2, 3 and 4 show a retro-reflective marker sphere 102 accordingto one embodiment of the present invention. Retro-reflective markersphere 102 comprises a core ball 112 on which is mounted an upperretro-reflective covering piece 114 and a lower retro-reflectivecovering piece 116. Upper retro-reflective covering piece 114 and lowerretro-reflective covering piece 116 are generally hemispherical inshape. Where upper retro-reflective covering piece 114 and lowerretro-reflective covering piece 116 meet there is a seam 118. Lowerretro-reflective covering piece 116 includes a circular opening 120.Core ball 112, shown in detail in FIGS. 5 and 6, has a generallyspherical body portion 132, a mounting recess 134, a mounting base 136,an upper central circular (dimple) divet 138 and eight upper peripheralcircular (dimples) divets 140. Mounting recess 134 is circular incross-section and has a circular opening 144 centered in mounting base136. Mounting base 136 is octagonal in shape, i.e., mounting base 136has eight sides 146 and eight corners 148. When assembled, as shown inFIGS. 1, 3 and 4, mounting base 136 extends through circular opening 120of lower retro-reflective covering piece 116 so that a lower surface 152of mounting base 136 is spaced proximally from a lower edge 154 ofcircular opening 120 and lower retro-reflective covering piece 116.Mounting recess 134 includes a recess lower portion 156 having acylindrical wall 158, a recess upper portion 160 having a cylindricalwall 162 and a rounded upper end 164. Recess lower portion 156 includesan interior screw thread 166 on cylindrical wall 158. Recess lowerportion 156 is larger in diameter than recess upper portion 160. Recessupper portion 160 does not have an interior screw thread. Recess lowerportion 156 and recess upper portion 160 each have a circularcross-section. In the embodiment shown, upper retro-reflective coveringpiece 114 covers an upper half 172 of core ball 112, and lowerretro-reflective covering piece 116 covers a lower half 174 of core ball112. A circular ledge 182 is formed at an upper end 184 of recess lowerportion 156 due to the fact that recess lower portion 156 is larger indiameter than recess upper portion 160. Retro-reflective marker sphere102 and core ball 112 have an axis shown by double-headed dashed arrow190, shown in FIGS. 1 and 4, that extends through the center of mountingrecess 134. Together, upper retro-reflective covering piece 114 andlower retro-reflective covering piece 116 form a retro-reflectivecovering 192 that is generally spherical in shape.

FIG. 7 shows a medical device 702 on which are mounted threeretro-reflective marker spheres 102. Medical device 702 is mounted by amounting device 706 on a human foot 712 extending through an opening 714in a covering blanket 716. Medical device 702 includes three arms 722,724 and 726.

In FIG. 7, the three retro-reflective marker spheres provide a preciselocation in three-dimensional space of the contact area between theprobe and the foot of the patient. The position of each of theretro-reflective marker spheres is registered using the vision systemwhich extrapolates the position of probe relative to the foot of thepatient.

FIG. 8 shows a mounting post 812 that is mounted on an upper surface 814of a circular end 816 of arm 722 of medical device 702. Mounting post812 includes a post base 818, a cylindrical post lower portion 820, apost neck portion 822, a post middle portion 824, a cylindrical postupper portion 826 and a post rounded end 828. Post middle portion 824includes an exterior screw thread 832. Post lower portion 820 includesan upper surface 842.

FIG. 9 shows retro-reflective marker sphere 102 mounted on mounting post812. Interior screw thread 166 of retro-reflective marker sphere 102screws onto exterior screw thread 832. Lower surface 152 of mountingbase 136 abuts upper surface 842 of post lower portion 820, therebyensuring that retro-reflective marker sphere 102 is mounted properly onmounting post 812. Post upper portion 826 and post rounded end 828 arereceived by recess upper portion 160 and rounded upper end 164,respectively, of mounting recess 134 of retro-reflective marker sphere102 to help maintain the alignment of retro-reflective marker sphere 102on mounting post 812 in the direction shown by double-headed arrow 912,i.e., the axial direction for mounting post 812. A gap 922 is formedbetween a top 924 of exterior screw thread 832 and ledge 182 due tolower surface 152 of mounting base 136 abutting upper surface 842 ofpost lower portion 820 prior to exterior screw thread 832 travellingfully upward in interior screw thread 166.

FIG. 10 shows a retro-reflective marker sphere 1002 according to oneembodiment of the present invention that may be snapped onto mountingpost 812 as shown in FIGS. 11 and 12. Retro-reflective marker sphere1002 comprises a core ball 1012 on which is mounted an upperretro-reflective covering piece 1014 and a lower retro-reflectivecovering piece 1016. Upper retro-reflective covering piece 1014 andlower retro-reflective covering piece 1016 are generally hemisphericalin shape. Where upper retro-reflective covering piece 1014 and lowerretro-reflective covering piece 1016 meet there is a seam 1018. Lowerretro-reflective covering piece 1016 includes a circular opening 1020.Core ball 1012 has a generally spherical body portion 1032, a mountingrecess 1034, a mounting base 1036, an upper central circular (dimple)divet 1038 and eight upper peripheral circular (dimples) divets 1040.Mounting recess 1034 is circular in cross-section and has a circularopening 1044 centered in mounting base 1036. Mounting base 1036 isoctagonal in shape, i.e., mounting base 1036 has eight sides 1046 andeight corners (not shown). Mounting base 1036 extends through circularopening 1020 of lower retro-reflective covering piece 1016 so that alower surface 1052 of mounting base 1036 is spaced proximally from alower edge 1054 of circular opening 1020 and lower retro-reflectivecovering piece 1016. Mounting recess 1034 includes a recess lowerportion 1056 having a cylindrical wall 1058, a recess upper portion 1060having a cylindrical wall 1062 and a rounded upper end 1064. Recesslower portion 1056 includes a semi-locking interior screw thread 1066 atan upper end 1068 of recess lower portion 1056. Semi-locking interiorscrew thread 1066 is “semi-locking” because semi-locking interior screwthread 1066 has a rounded ridge 1070 that does not fully mate withgroove 1072 of exterior screw thread 832 of mounting post 812, as shownin FIG. 12. The interaction of semi-locking interior screw thread 1066and exterior screw thread 832 of mounting post 812, shown in detail inFIG. 12 corresponding to dashed-circled region 1074 of FIG. 11, causesan audible “snap” when retro-reflective marker sphere 1002 is snappedonto mounting post 812.

A lower section 1080 of recess lower portion 1056 does not include ascrew thread to allow retro-reflective marker sphere 1002 to be snappedonto mounting post 812. Recess lower portion 1056 is larger in diameterthan recess upper portion 1060. Recess upper portion 1060 does not havean interior screw thread. Recess lower portion 1056 and recess upperportion 1060 each have a circular cross-section. In the embodimentshown, upper retro-reflective covering piece 1014 covers an upper half1082 of core ball 1012, and lower retro-reflective covering piece 1016covers a lower half 1084 of core ball 1012. Retro-reflective markersphere 1002 and core ball 1012 have an axis shown by double-headeddashed arrow 1090 in FIG. 10 that extends through the center of mountingrecess 1034. Together, upper retro-reflective covering piece 1014 andlower retro-reflective covering piece 1016 form a retro-reflectivecovering 1092 that is generally spherical in shape.

Although in the embodiment of the present invention shown in FIGS. 1, 2,3, 4, 5 and 6 the mounting base is octagonal in shape, i.e., themounting base has an octagonal-shaped cross-section in a planeperpendicular to the axis of the retro-reflective marker sphere and thecore ball, the mounting base may have various shapes such as circular,oval, triangular, star-shaped, square, rectangular, pentagonal,hexagonal, etc. In some embodiments of the present invention, themounting base may be a shape such as a square, rectangle, pentagon,hexagon, octagon, etc., which has corners that allow for more precisemolding of the core ball. For example, the corners/edges prevent thecore ball from turning in an injection mold. The corners/edges alsoprevent counter-rotation of the core ball during unscrewing of a corepin used in forming the threaded mounting recess during injectionmolding.

Although in the embodiments described above and shown in the drawings,the sides of the mounting base are straight, in other embodiments thesides of the mounting base may be curved in either a convex or concavefashion. Also, even when the sides of mounting base are curved, thesides may still meet at corners.

In some embodiments of the present invention, the corners of themounting base may be formed by one or more rectangular spokes or bytriangular points that radiate from one or more sides of a mounting basethat is otherwise polygonal, circular or oval in shape. In oneembodiment of the present invention the rectangular spokes may radiatefrom the mounting base like the four arms of a plus sign, the six armsof an asterisk, etc. In one embodiment of the present invention, thetriangular points may radiate from the sides of the mounting base likethe points of a four, five, six, seven, eight, etc. pointed star.

FIG. 13 shows a retro-reflective marker sphere 1302 according to oneembodiment of the present invention which includes mounting base 1312that is triangular in shape, i.e., mounting base 1312 has three sides1314 and three corners 1316. In the center of mounting base 1312 is amounting recess 1322 that is similar to mounting recess 134. FIG. 14shows a retro-reflective marker sphere 1402 according to one embodimentof the present invention which includes mounting base 1412 that issquare in shape. Mounting base 1412 has four sides 1414 and four corners1416. In the center of mounting base 1412 is a mounting recess 1422 thatis similar to mounting recess 134. FIG. 15 shows a retro-reflectivemarker sphere 1502 according to one embodiment of the present inventionwhich includes mounting base 1512 that is hexagonal in shape. Mountingbase 1512 has six sides 1514 and six corners 1516. In the center ofmounting base 1512 is a mounting recess 1522 that is similar to mountingrecess 134. Other than the shapes of their respective mounting bases1312, 1412 and 1512, retro-reflective marker spheres 1302, 1402 and 1502are identical to retro-reflective marker sphere 102.

In some embodiments of the present invention, the mounting base of theretro-reflective marker sphere may include one or more alignmentindicators. For example, FIGS. 16, 17, 18, 19 and 20 show examples ofsome of the types of alignment indicators that may be used to determineif a retro-reflective marker sphere is aligned properly on a mountingpost. FIG. 16 shows a retro-reflective marker sphere 1602 according toone embodiment of the present invention having an octagonal-shapedmounting base 1612 that has a bright contrasting color shown by apattern 1614 in comparison with a retro-reflective covering 1616 ofretro-reflective marker sphere 1602 that may be easily seen by a user.The bright contrasting color functions as an alignment indicator,allowing the proper alignment of retro-reflective marker sphere 1602 onpost lower portion 820 of mounting post 812 to be confirmed by theperson mounting retro-reflective marker sphere 1602 on mounting post812.

FIG. 17 shows a retro-reflective marker sphere 1702 according to oneembodiment of the present invention having an octagonal-shaped mountingbase 1712 with a side 1714 that has a bright contrasting color, shown bya pattern 1716, in comparison with a retro-reflective covering 1718 ofretro-reflective marker sphere 1702 and thus functions as an alignmentindicator. The bright contrasting color allows the proper alignment ofretro-reflective marker sphere 1702 on post lower portion 820 ofmounting post 812 to be confirmed by the person mountingretro-reflective marker sphere 1702 on mounting post 812.

In one embodiment, the “bright contrasting color” is a variation in thesubstance with respect to light reflected by one or more sides of themounting base. The contrasting color may be observed visually and/or bymeasurement of hue, saturation and brightness of the reflected lightfrom the one or more sides of the mounting base.

FIG. 18 shows a retro-reflective marker sphere 1802 according to oneembodiment of the present invention having an octagonal-shaped mountingbase 1812 with a side 1814 having an alignment line 1816 that has abright contrasting color in comparison with a retro-reflective covering1818 of retro-reflective marker sphere 1802 and thus functions as analignment indicator. The bright contrasting color allows the properalignment of retro-reflective marker sphere 1802 on post lower portion820 of mounting post 812 to be confirmed by the person mountingretro-reflective marker sphere 1802 on mounting post 812.

FIG. 19 shows a retro-reflective marker sphere 1902 according to oneembodiment of the present invention having an octagonal-shaped mountingbase 1912 with a side 1914 having an alignment dot 1916 that has abright contrasting color in comparison with a retro-reflective covering1918 of retro-reflective marker sphere 1902 and thus functions as analignment indicator. The bright contrasting color allows the properalignment of retro-reflective marker sphere 1902 on post lower portion820 of mounting post 812 to be confirmed by the person mountingretro-reflective marker sphere 1902 on mounting post 812.

FIG. 20 shows a retro-reflective marker sphere 2002 according to oneembodiment of the present invention having an octagonal-shaped mountingbase 2012 with sides 2014 and 2016 having respective alignment stars2018 and 2020 that each have a bright contrasting color in comparisonwith a retro-reflective covering 2032 of retro-reflective marker sphere2002 and thus function as alignment indicators. The bright contrastingcolor allows the proper alignment of retro-reflective marker sphere 2002on post lower portion 820 of mounting post 812 to be confirmed by theperson mounting retro-reflective marker sphere 2002 on mounting post812.

FIG. 21 shows a blister strip 2102 comprising ten blister packs 2112according to one embodiment of the present invention. Enclosed in eachblister pack 2112 is one retro-reflective marker sphere 102. Blisterstrip 2102 includes a transparent or translucent pocket layer 2122 and abacking layer 2124 joined to pocket layer 2122. Pocket layer 2122includes dome-shaped pockets 2132 and flat portions 2134. The presenceof pockets 2132 forms openings 2136 that are each slightly larger indiameter than each retro-reflective marker sphere 102. Each blister pack2112 is separated from one or two adjacent blister packs 2112 by aperforation 2142 that extends at least through pocket layer 2122 and mayextend through backing layer 2124. Perforation 2142 allows neighboringblister packs 2112 to be separated from each other by a user tearingpocket layer 2122 and backing layer 2124 along a perforation 2142between neighboring blister packs 2112. FIG. 22 shows a cross-section ofone retro-reflective marker sphere 102 in a blister pack 2112.

Although FIG. 21 shows a blister strip used with one particular type ofretro-reflective marker sphere, the blister strips of the presentinvention may be used with various types of retro-reflective markerspheres, including retro-reflective marker spheres for both threaded andsnap-on mounting posts.

FIGS. 23 and 24 show a retro-reflective marker sphere 102 in a blisterpack 2302 according to one embodiment of the present inventioncomprising a transparent or translucent pocket layer 2312 and a backinglayer 2314 joined to pocket layer 2312. Backing layer 2314 includes anoctagonal-shaped recessed portion 2316. Pocket layer 2312 includes adome-shaped pocket 2322. Mounting base 136 fits into octagonal-shapedrecessed portion 2316 to thereby help keep retro-reflective markersphere 102 in a right-side-up orientation in blister pack 2302. Pocket2322 contains retro-reflective marker sphere 102. A series of blisterpacks 2302 may be part of a blister strip similar to blister strip 2102.

Although the recess shown in FIGS. 23 and 24 is octagonal-shaped, therecess in the backing layer of the present invention may have variousshapes including circular, oval, lozenge-shaped, etc., as well asvarious polygonal shapes.

FIGS. 25 and 26 show a retro-reflective marker sphere 102 in a blisterpack 2502 according to one embodiment of the present inventioncomprising a transparent or translucent pocket layer 2512 and a backinglayer 2514 joined to pocket layer 2512. Backing layer 2514 includes acircular-shaped opening 2516. Mounting base 136 extends throughcircular-shaped opening 2516 to thereby help keep retro-reflectivemarker sphere 102 in right-side-up orientation in blister pack 2502.FIG. 25 shows a protective layer 2522 that is joined to backing layer2514 to protect mounting base 136. Protective layer 2522 is joined tobacking layer 2514 using an adhesive 2524. Adhesive 2524 may not bepresent in the region beneath mounting base 136 to avoid adhesive 2524possibly sticking to mounting base 136. Adhesive 2524 on protectivelayer 2522 is sufficiently weak to allow protective layer 2522 to beremoved from backing layer 2514. Once protective layer 2522 is removedfrom backing layer 2514, retro-reflective marker sphere 102 may bescrewed onto a mounting post, such as mounting post 812 (not shown inFIGS. 25 and 26), while still in blister pack 2502. Retro-reflectivemarker sphere 102 may then be removed from blister pack 2502. Pocketlayer 2512 includes a dome-shaped pocket 2532 that containsretro-reflective marker sphere 102. A series of blister packs 2502 maybe part of a blister strip similar to blister strip 2102.

In one embodiment of the present invention, a user may screwretro-reflective marker sphere 102 onto a mounting post by graspingretro-reflective marker sphere 102 through pocket 2532 and turningretro-reflective marker sphere 102 on the thread of the mounting post.

Although the opening in the backing layer in FIGS. 25 and 26 iscircular, the opening could be octagonal in shape, to match the shape ofthe mounting base of the retro-reflective marker sphere, or any othershape, such as oval, lozenge-shaped, etc.

FIG. 27 shows a 4×4 blister card 2702 comprising sixteen blister packs2712 according to one embodiment of the present invention. Enclosed ineach blister pack 2712 is one retro-reflective marker sphere 102.Blister card 2702 includes a transparent or translucent pocket layer2722 and a backing layer 2724 joined to pocket layer 2722. Pocket layer2722 includes dome-shaped pockets 2732 and flat portions 2734. Thepresence of pockets 2732 forms openings 2736 that are each slightlylarger in diameter than each retro-reflective marker sphere 102. Eachblister pack 2712 is separated from two, three or four adjacent blisterpacks 2712 by perforations 2742 and 2744 that extend at least throughpocket layer 2722 and may extend through backing layer 2724.Perforations 2742 and 2744 allow neighboring blister packs 2712 to beseparated from each other by a user tearing pocket layer 2722 andbacking layer 2724 along perforation 2742. Perforations 2742 and 2744are oriented in respective perpendicular directions shown bydouble-headed arrows 2752 and 2754, respectively.

In one embodiment of the present invention, a blister strip or blistercard may be produced by vacuum-forming or thermo-forming the “pockets.”Compression plates or rollers may be used to apply the backing heatersthat adhere the backing substrates to the pocket layer.

Although FIG. 27 shows a blister card used with one particular type ofretro-reflective marker sphere, the blister cards of the presentinvention may be used with various types of retro-reflective markerspheres, including retro-reflective marker spheres for both threaded andsnap-on posts.

In some embodiments of the present invention, blister packs similar toblister packs 2302 and 2502 may be arranged in a two-dimensional blistercard similar to blister card 2702. Also, a blister card of the presentinvention may have any number of blister packs in any two-dimensionalarrangement.

In one embodiment of the present invention, the pocket layer of eachblister pack is made of a transparent or translucent plastic, and thebacking layer may be made of materials such as plastic, paper, cloth,metal foil, a combination of materials, etc., to which the pocket layeris adhered using an adhesive that allows the pocket layer to be removedfrom the backing layer, thereby allowing a retro-reflective markersphere to be removed from the blister pack by a user.

In one embodiment of the present invention, the pocket layer of eachblister pack is made of a transparent or translucent plastic, and thebacking layer is made of a rupturable material, such as metal foil,similar to the blister packs used with pills and tablets. The backinglayer may be joined to the pocket layer using an adhesive, bythermoforming the backing layer to the pocket layer, or by any otherprocess for joining the backing layer of a blister pack to the pocketlayer of a blister pack. Such a configuration allows a retro-reflectivemarker sphere to be removed from a blister pack by pressing down on thedome-shaped pocket of the blister pack, thereby forcing theretro-reflective marker sphere through the opening in the pocket layerand rupturing the rupturable material of the backing layer.

Although the blister packs shown in the drawings are shown as being usedwith a particular retro-reflective marker sphere of the presentinvention, the blister packs of the present invention may be used withvarious types of retro-reflective marker spheres, such as the snap-onretro-reflective spheres shown in FIGS. 10, 28, 29, 30, 31, 32, 33, 34,35 and 36, as well as with other types of retro-reflective markerspheres.

FIGS. 28, 29, 30 and 31 show a retro-reflective marker sphere 2802according to one embodiment of the present invention. Retro-reflectivemarker sphere 2802 is a snap-on retro-reflective marker sphere that isdesigned to snap onto a snap-on mounting post of a medical device (notshown in FIGS. 28, 29, 30 and 31). Retro-reflective marker sphere 2802comprises a core ball 2812 on which is mounted an upper retro-reflectivecovering piece 2814 and a lower retro-reflective covering piece 2816.Upper retro-reflective covering piece 2814 and lower retro-reflectivecovering piece 2816 are generally hemispherical in shape. Where upperretro-reflective covering piece 2814 and lower retro-reflective coveringpiece 2816 meet there is a seam 2818. Lower retro-reflective coveringpiece 2816 includes a circular opening 2820. Core ball 2812, shown indetail in FIGS. 32, 33, 34, 35 and 36, has a generally spherical bodyportion 2832, a mounting recess 2834, an upper central circular (dimple)divet 2838 and sixteen upper peripheral circular (dimples) divets 2840.Mounting recess 2834 is circular in cross-section and has a circularopening 2844. In the embodiment shown, upper retro-reflective coveringpiece 2814 covers an upper half 2872 of core ball 2812, and lowerretro-reflective covering piece 2816 covers a lower half 2874 of coreball 2812. Retro-reflective marker sphere 2802 and core ball 2812 havean axis shown by double-headed dashed arrow 2890, shown in FIG. 28, thatextends through the center of mounting recess 2834. Together, upperretro-reflective covering piece 2814 and lower retro-reflective coveringpiece 2816 form a retro-reflective covering 2892 that is generallyspherical in shape.

FIGS. 32, 33, 34, 35 and 36 show core ball 2812 and details of mountingrecess 2834. Mounting recess 2834 includes a flared recess base portion3412, a cylindrical recess lower portion 3414, a cylindrical recesswaist portion 3416, a recess chamfered portion 3418, a cylindricalrecess middle portion 3420, a recess frustoconical portion 3422, acylindrical recess upper portion 3424 and a recess top 3426. Becauserecess waist portion 3416 is smaller in diameter than recess lowerportion 3414, a ledge 3432 is formed at an upper end 3434 of recesslower portion 3414. Recess waist portion 3416 has a cylindrical wall3436. Details of dashed-circled regions 3442 and 3444 are shown in FIGS.35 and 36, respectively. Although as shown in FIG. 35 the angle of anangled wall 3452 of recess base portion 3412 with respect to a line 3454parallel to the axis of core ball 2812 is 45°, this angle may varydepending on the particular mounting post on which retro-reflectivemarker sphere 2802 is to be mounted. Similarly, although as shown inFIG. 36 the angle of an angled wall 3462 of recess frustoconical portion3422 with respect to a line 3464 parallel to the axis of core ball 2812is 30°, this angle may vary depending on the particular mounting post onwhich retro-reflective marker sphere 2802 is to be mounted. Together,ledge 3432, cylindrical wall 3436 and angled wall 3452 define a raisedrim 3472 that projects into mounting recess 2834.

FIG. 37 shows a medical device 3702 on which are mounted threeretro-reflective marker spheres 2802. Medical device 3702 functionssimilarly to medical device 702. Medical device 3702 is mounted by amounting device 3706 on a human foot 3712 extending through an opening3714 in a covering blanket 3716. Medical device 3702 includes three arms3722, 3724 and 3726.

FIG. 38 shows a snap-on mounting post 3812 that is mounted on an uppersurface 3814 of a circular end 3816 of arm 3722 of medical device 3702.Mounting post 3812 includes a post base 3818, a cylindrical post lowerportion 3820, a cylindrical post middle portion 3824, a post upperchamfered portion 3826, a cylindrical post upper portion 3828, a postfrustoconical portion 3830 and a post top 3832. Post lower portion 3820includes an upper surface 3842 having a circular peripheral edge 3844.Together post upper chamfered portion 3826, post upper portion 3828,post frustoconical portion 3830 and post top 3832 are part of a postupper end 3852 having a post upper end surface 3854.

FIG. 39 shows retro-reflective marker sphere 2802 snapped onto snap-onmounting post 3812 by forcing retro-reflective marker sphere 2802 ontosnap-on mounting post 3812. Because core ball 2812 is made of aresilient material, mounting recess 2834 is able to spread open slightlyso that raised rim 3472 can slide along post upper end surface 3854 asretro-reflective marker sphere 2802 is forced onto snap-on mounting post3812. Raised rim 3472 eventually reaches post middle portion 3824 andsnaps into place beneath post upper end 3852. Retro-reflective markersphere 2802 is held in place on snap-on mounting post 3812 by post upperend 3852 being trapped between recess frustoconical portion 3422 andraised rim 3472. angled wall 3452 of recess base portion 3412 abutscircular peripheral edge 3844 upper surface 3842 of post lower portion3820. Snap-on mounting post 3812 has an axis 3912.

In some embodiments of the present invention, a blister pack of thepresent invention may include two or more backing layers. For example,one backing layer may be made of a stiff or semi-stiff material such ascardboard or a stiff plastic that provides structural stability to theblister pack. In such an embodiment, the backing layer made of the stiffor semi-stiff material may include openings that are aligned with and incommunication with openings of the pockets of the pocket layer. Eachopening in the backing layer may have the same shape as the opening atthe bottom of the respective pocket with which the opening of thebacking layer is aligned. The openings in the backing layer also may beroughly the same diameter as the openings of the pockets or may belarger than the openings of the pockets. The two backing layers may bejoined to each other by various means, such as an adhesive, and thebacking layer made of the stiffer material is in turn joined to thepocket layer.

FIG. 40 shows an example of a blister pack 4002 according to oneembodiment of the present invention having two backing layers, i.e.,upper backing layer 4004 and lower backing layer 4006. Lower backinglayer 4006 is joined to a lower surface 4008 of upper backing layer4004. Joined to an upper surface 4010 of upper backing layer 4004 is apocket layer 4012 having a dome-shaped pocket 4014. Upper backing layer4004 may be made of a stiff or semi-stiff material such as cardboard ora stiff plastic that provides structural stability to blister pack 4002.Lower backing layer 4006 may be made of a rupturable or a non-rupturablematerial. FIG. 40 shows a retro-reflective marker sphere 4022 in blisterpack 4002. Retro-reflective marker sphere 4022 includes a generallyspherical core ball 4024 to which is adhered a generally sphericalretro-reflective covering 4026. Core ball 4024 includes a mountingrecess 4028 having an interior screw thread 4030. Retro-reflectivecovering 4026 is comprised of a generally hemispherical upperretro-reflective covering piece 4032 and a generally spherical lowerretro-reflective covering piece 4034 that meet at a seam 4036. Lowerretro-reflective covering piece 4034 includes a circular opening 4038.Upper backing layer 4004 includes an opening 4040 that is aligned and incommunication with an opening 4042 of pocket 4014. A lower edge 4044 oflower retro-reflective covering piece 4034 abuts lower backing layer4006. There is a gap 4052 between a base 4054 of core ball 4024 andlower backing layer 4006. Mounting recess has a distal end 4062.

If lower backing layer 4006 is made of a rupturable material,retro-reflective marker sphere 4022 may be removed from blister pack4002 by a user pressing down on pocket 4014, to thereby forcingretro-reflective marker sphere 4022 through opening 4042 in upperbacking layer 4004 and thereby rupturing the rupturable material oflower backing layer 4006.

If lower backing layer 4006 is made of a non-rupturable material, pocketlayer 4012 may be adhered to upper surface 4010 of upper backing layer4004 by an adhesive that allows pocket layer 4012 to be manually removedfrom upper backing layer 4004 to thereby open blister pack 4002.

A series of blister packs 4002 may be part of a blister strip similar toblister strip 2102. Blister packs 4002 may also be part of a blistercard similar to blister card 2702.

Although only one type of blister pack employing two backing layers isshown in FIG. 40, various types of blister packs may be made using twolayers according to various embodiments of the present invention. Forexample, a rupturable layer of a two-backing layer blister pack mayinclude a recess for a mounting base such as that shown in FIGS. 23 and24 or an opening for a mounting base such as that shown in FIGS. 25 and26.

Although one type of retro-reflective marker sphere is shown packaged inthe blister pack shown in FIG. 40, a blister pack with two backinglayers may be used with various types of retro-reflective markerspheres.

Although only two backing layers are shown in FIG. 40, amultiple-backing-layer blister pack of the present invention may havethree or more backing layers.

FIGS. 41 and 42 show a retro-reflective marker sphere 102 in a blisterpack 4102 according to one embodiment of the present inventioncomprising a transparent or translucent pocket layer 4112 and a backinglayer 4114 joined to pocket layer 4112. Backing layer 4114 includes aoctagonal-shaped opening 4116. Mounting base 136 extends throughcircular-shaped opening 4116 to thereby help keep retro-reflectivemarker sphere 102 in right-side-up orientation in blister pack 4102.FIG. 41 shows a protective layer 4122 that is joined to backing layer4114 to protect mounting base 136. Protective layer 4122 is joined tobacking layer 4114 using an adhesive 4124. Adhesive 4124 may not bepresent in the region beneath mounting base 136 to avoid adhesive 4124possibly sticking to mounting base 136. Adhesive 4124 on protectivelayer 4122 is sufficiently weak to allow protective layer 4122 to beremoved from backing layer 4114. Once protective layer 4122 is removedfrom backing layer 4114, retro-reflective marker sphere 102 may bescrewed onto a mounting post, such as mounting post 812 (not shown inFIGS. 41 and 42), while still in blister pack 4102. Retro-reflectivemarker sphere 102 may then be removed from blister pack 4102. Pocketlayer 4112 includes a dome-shaped pocket 4132 that containsretro-reflective marker sphere 102. A series of blister packs 4102 maybe part of a blister strip similar to blister strip 2102.Octagonal-shaped opening 4116 includes eight sides 4146 and eightcorners 4148.

In one embodiment of the present invention, a user may screwretro-reflective marker sphere 102 onto a mounting post by graspingretro-reflective marker sphere 102 through pocket 4132 and turningretro-reflective marker sphere 102 on the thread of the mounting post.In this case sides 4146 and corners 4148 of octagonal-shaped opening4116 engage respective sides 146 and corners 148 of mounting base 136 toaid in turning retro-reflective marker sphere 102.

In one embodiment of the present invention, a user may screwretro-reflective marker sphere 102 onto a mounting post by graspingpocket 4132 and turning pocket 4132 to cause sides 4146 and corners 4148of octagonal-shaped opening 4116 to engage respective sides 146 andcorners 148 of mounting base 136 thereby turn retro-reflective markersphere 102 and screw retro-reflective marker sphere 102 onto themounting post.

In one embodiment of the present invention, the core ball of aretro-reflective marker sphere of the present invention may be made ofan injection-moldable plastic such as a thermoplastic polyesterelastomer. Other types of materials that may be used to form the coreball include polyethylene, polypropylene and other thermoplasticelastomers.

FIG. 43 shows core ball 2812 and details of mounting recess 2834.Mounting recess 2834 includes a flared recess base portion 3412, acylindrical recess lower portion 3414, a cylindrical recess waistportion 3416, a recess chamfered portion 3418, a cylindrical recessmiddle portion 3420, a recess frustoconical portion 3422, a cylindricalrecess upper portion 3424 and a recess top 3426. Because recess waistportion 3416 is smaller in diameter than recess lower portion 3414, aledge 3432 is formed at an upper end 3434 of recess lower portion 3414.Recess waist portion 3416 has a cylindrical wall 3436. Although theangle of an angled wall 3452 of recess base portion 3412 with respect toa axis 2890 of core ball 2812 is 45°, this angle may vary depending onthe particular mounting post on which retro-reflective marker sphere2802 is to be mounted. Together, ledge 3432, cylindrical wall 3436 andangled wall 3452 define a raised rim 3472 that projects into mountingrecess 2834.

The material 4312 of core ball 2812 may comprise a filler material suchas an MRI filling material. The MRI filling material is capable of beingregistered on machine equipment utilized in an MRI exam or procedure.Utilizing MRI filling material eliminates additional manufacturingprocesses and materials for constructing retro-reflective surfaces onthe outside of core ball 2812. Disclosed embodiments of the MRI fillingmaterial may comprise water, watery liquids, gel or fat. In somedisclosed embodiments, the viscosity ranges of the MRI filling materialmay range between approximately 1 cP (Centipoise) or cSt (Centistokes)to 1840 cp or cSt. Material 4312 is contained within core ball 2812. Inone disclosed embodiment, material 4312 is encapsulated within a cavityof core ball 2812 between mounting recess 2834 and a covering layer4314. An access hole may be created in upper peripheral circular(dimple) divet 2840, but below covering layer 4314, to introducematerial 4312 within the cavity of core ball 2812. Once the cavity ofcore ball 2812 is filled with the filler material, the access hole maybe plugged to prevent leakage therefrom. Because the access hole isdisposed in upper peripheral circular (dimple) divet 2840 and belowcovering layer 4314, no interference occurs at covering layer 4314. Thisfeature reduces additional manufacturing steps for generating thedisclosed design in an efficient and functional manner. Thus, in someembodiments, MRI filling material, such as water, watery liquids, gel orfat, may be injected within the cavity of core ball 2812 to provide afiller material.

In some embodiments of the present invention the retro-reflectivecovering of a retro-reflective marker sphere may be a two-pieceretro-reflective covering, as shown in FIGS. 1, 2, 3, 4, 5, 6, 10, 28,29, 30, 31, 32, 33, 34, 35 and 36. However, in other embodiments of thepresent invention, the retro-reflective covering may be made as a singlepiece. In one embodiment of the present invention, the upper and lowerretro-reflective coverings may each be formed by thermoforming a pieceof retro-reflective material to the appropriate trimming of the materialbefore and/or after thermoforming. Such thermoforming allows thethickness of the retro-reflective covering to be controlled to aconstant thickness throughout the retro-reflective covering.

In one embodiment of the present invention, such as shown in FIGS. 1, 2,3, 4, 5, 6, 10, 28, 29, 30, 31, 32, 33, 34, 35 and 36, there is no orvirtually no gap at the seam between the upper and lowerretro-reflective covering pieces. In one embodiment, the gap may beminimized or eliminated by controlling the dimensions of the formed andcut hemispheres and designing the upper and lower retro-reflectivecovering pieces so that the open end of each of the upper and lowerretro-reflective covering pieces butt up to each other during automatedassembly. The upper and lower retro-reflective covering piece may beadhered to the core ball by applying a UV-curable adhesive via syringetip, blade, spray or brush to the core ball and then curing the bondthrough the upper and lowering covering pieces with a combination oflight and/or UV-ray intensity and time. Similar procedures may also beemployed to eliminate or reduce the gaps in retro-reflective coveringscomprising three or more pieces.

In one thermoforming process that may be used to form the upper andlower retro-reflective coverings, a starting material is chosen that isconstant in thickness. A vacuum forming is used that allows an entiresheet of the retro-reflective covering material to be heated, stretchedand then vacuum-formed into multiple identical-shaped nests to formexact replicas of each other. The heating, stretching and vacuumapplication steps of the process may be controlled to provideconsistency from cycle to cycle (each forming multiple hemisphericalcoverings). The consistent manner in which the material is heated andstretched, and the equal application of the vacuum across the surface ofeach section of covering to be formed, creates a consistent thicknessacross the entire hemisphere of the retro-reflective covering.

In one embodiment of the present invention, the thickness of theretro-reflective covering may vary by no more than 0.003″ (0.00762 cm)throughout the retro-reflective covering. Suitable retro-reflectivematerials include 3M 8350 Scotchlite reflective pressure sensitiveadhesive (PSA) films (made by 3M). In one embodiment of the presentinvention, the retro-reflective coating may be a layer of aretro-reflective paint.

The upper and lower retro-reflective coverings may be mounted on thecore ball using an adhesive. Suitable adhesives include cyanoacrylates,light-cure adhesives, UV-cure adhesives, etc. When a UV-cure adhesive isused, the adhesive may be cured by exposing the covered core ball to UVlight to adhere the upper and lower retro-reflective coverings to thecore ball.

Although in some embodiments of the present invention shown in FIGS. 1,2, 3, 4, 5, 6, 10, 28, 29, 30, 31, 32, 33, 34, 35 and 36 the core ballhas eight smaller circular peripheral divets surrounding one largercentral circular divet, the core ball may have various numbers, sizesand shapes of divets, and the divets may be arranged in variouspatterns. One purpose of the central divet is to provide a recess at thelocation of the gate for the injection mold cavity for the core ball.Because the gate for the cavity for the core ball is located in arecessed region, i.e., the central divet, when the core ball is removedfrom the runner after molding, it is not necessary to sand down anyremaining plastic material at the gate. The number and/or arrangement ofperipheral divets on a core ball may be used to identify the cavity of amold in which a particular core ball is formed. For example, eightperipheral divets may indicate one cavity in a mold, seven peripheraldivets may identify a second cavity of a mold, etc. When multiple moldsare used to form core balls, the number and/or arrangement of peripheraldivets may identify a particular cavity of a particular mold. Also,although in the embodiments of the present invention shown in FIGS. 1,2, 3, 4, 5, 6, 10, 28, 29, 30, 31, 32, 33, 34, 35 and 36 the core ballincludes divets, in other embodiments of the present invention, the coreball may not include either a central divet and/or peripheral divets. Ina core ball that does not include a central divet, the surface of thecore ball may be sanded or otherwise smoothed to remove plastic materialremaining at the gate for the core ball after the core ball has beenremoved from a runner after injection molding.

In one embodiment of the present invention, the core ball of aretro-reflective marker sphere may be radiopaque for use in CT scanning(computed tomography scanning). In some embodiments of the presentinvention, the retro-reflective marker may be suitable for using inmagnetic resonance imaging (MRI).

In one embodiment of the present invention, the core ball may have aradiopaque loading of >12%, i.e., the core ball is greater than 12%radiopaque. In one embodiment of the present invention, the core ballmay be made radiopaque by loading barium into the resin for the coreball prior to injection molding of the core ball. In one embodiment ofthe present invention, the mounting recess of the core ball may bedesigned to allow the retro-reflective marker sphere to be snapped ontoa mounting post.

Although in some embodiments of the present invention, theretro-reflective covering and covering pieces of the retro-reflectivemarker sphere may be gray and/or silver in color, in other embodimentsof the present invention, the retro-reflective coverings and coveringpieces may be gold, white or chrome in color to provide betterreflectivity than retro-reflective coverings and covering pieces thatare gray and/or silver in color. Examples of materials that may be usedfor gold, white and chrome retro-reflective coverings include glassbeads, reflective inks, reflective paints and reflective tapes.

In one embodiment of the present invention, the upper half and the lowerhalf of the core ball may have different colors to aid in determining ifthe upper retro-reflective covering and the lower retro-reflectivecovering are mounted properly on the core ball. If the upperretro-reflective covering or the lower retro-reflective covering is notmounted properly on the core ball, the upper or lower half of the coreball, respectively, will be visible. Based on the color visible, a userwill be able to determine if the upper retro-reflective covering pieceor the lower retro-reflective covering piece is not mounted properly onthe core ball.

In one embodiment of the present invention, the retro-reflective markerspheres may be compatible with Brainlab™ navigation systems. In oneembodiment of the present invention, retro-reflective marker spheres arevisible using x-ray and CT imaging. The retro-reflective marker spheresmay provide auto-registration and localization of anatomical structuresthat enable surgeons to wirelessly track the position and orientation ofany device from a frame of reference.

In one embodiment of the present invention, the retro-reflective markersphere may be made in one, two or more pieces of a retro-reflectivematerial. For example, a transparent plastic filled withretro-reflective filler material, such as solid or hollow microspheres,may be used to form an injection molded retro-reflective marker spherein or two pieces. If the retro-reflective microsphere is molded in twopieces, the two pieces may be joined using an adhesive and/or matingengagement structures on the two pieces. For example, one piece may bescrewed into the other piece, the two pieces may have one or morecombinations of tab recesses and mating tabs, the two pieces may haveone or more combinations of pin recesses and mating pins, etc. Examplesof filler materials for the transparent plastic to make the plasticretro-reflective include Scotchlite® glass microspheres made by 3M.

Having described the many embodiments of the present invention indetail, it will be apparent that modifications and variations arepossible without departing from the scope of the present inventiondefined in the appended claims. Furthermore, it should be appreciatedthat all examples in the present disclosure, while illustrating manyembodiments of the present invention, are provided as non-limitingexamples and are, therefore, not to be taken as limiting the variousaspects so illustrated.

While the present invention has been disclosed with references tocertain embodiments, numerous modifications, alterations and changes tothe described embodiments are possible without departing from the scopeand spirit of the present invention, as defined in the appended claims.Accordingly, it is intended that the present invention not be limited tothe described embodiments, but that it have the full scope defined bythe language of the following claims, and equivalents thereof.

What is claimed is:
 1. A device comprising a retro-reflective markersphere comprising: a core ball comprising: a generally spherical bodyportion, a mounting base extending from one end of the body portion ofthe core ball, and a mounting recess having a recess opening in themounting base and extending into the body portion of the core ball, anda retro-reflective covering on the core ball, the retro-reflectivecovering comprising an opening through which the mounting base of thecore ball extends, wherein the core ball is a single-piece core ball,wherein a flat lower surface of the mounting base is spaced proximallyfrom a lower edge of the opening of the retro-reflective covering, andwherein the mounting recess includes an interior screw thread forengaging an exterior screw thread of a mounting post when theretro-reflective marker sphere is mounted on the mounting post.
 2. Thedevice of claim 1, wherein the mounting recess includes an upper portionand a lower portion, wherein the interior screw thread is part of thelower portion, and wherein the lower portion includes the recess openingand is larger in diameter than the upper portion.
 3. The device of claim1, wherein the retro-reflective covering comprises only two pieces andwherein the opening in the retro-reflective covering is in only one ofthe two pieces.